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 ###Instrução: Quantos campeões de duplas houve no torneio Serbia f6 Futures?
 ###Tabelas: CREATE TABLE clausura_2006_standings (clausura_2006_standings_id AUTO_INCREMENT PRIMARY KEY, Place (Posición) INT, Team (Equipo) VARCHAR, Played (PJ) INT, Won (PG) INT, Draw (PE) INT, Lost (PP) INT, Goals Scored (GF) INT, Goals Conceded (GC) INT, +/- (Dif.) INT, Points (Pts.) INT) CREATE TABLE turkey (turkey_id AUTO_INCREMENT PRIMARY KEY, Downstream VARCHAR, Upstream VARCHAR, Bandwidth VARCHAR, Price TL VARCHAR, Every 1 GB VARCHAR, MAX VARCHAR) CREATE TABLE table_of_world_organization_of_the_scout_movement_members (table_of_world_organization_of_the_scout_movement_members_id AUTO_INCREMENT PRIMARY KEY, Country VARCHAR, Membership (from 2010) INT, Name of member organization VARCHAR, Year current Scouting organization joined WOSM VARCHAR, Year member organization was founded VARCHAR, Admits boys/girls VARCHAR) CREATE TABLE grand_slam_women's_singles_performance_timeline (grand_slam_women's_singles_performance_timeline_id AUTO_INCREMENT PRIMARY KEY, Tournament VARCHAR, 2008 VARCHAR, 2009 VARCHAR, 2010 VARCHAR, 2011 VARCHAR, 2012 VARCHAR) CREATE TABLE events (events_id AUTO_INCREMENT PRIMARY KEY, Tournament VARCHAR, Date VARCHAR, City VARCHAR, Country VARCHAR, Surface VARCHAR, Singles champions VARCHAR, Doubles champions VARCHAR)  
SELECT COUNT Doubles champions FROM events WHERE Tournament = Serbia F6 Futures